Death by ElectrocutionWhen you are planning to kill your Sims by electrocution, be sure to buy cheap electronics. The Sim using/attempting to fix the items should have no or very few Mechanical points. Once the electronic item has broken (you will see a crack in it and your option is to Repair it), have a Sim with no mechanical points attempt to fix the item. Sometimes Sims will only get a shock and not die, or the item will burst into flames. Things that cause electrocution:
Computers, TVs, Lighting (lightbulbs replaced), dishwashers, garbage compactors, stereos.Death details:An electrocuted Sim will be shocked and flicker as with most portrayals of electrocution.

Death by DrowningCreate a pool and have them get in. When they are in, remove the ladders or build a wall that prevents them from exiting the hottub.Death details:They swim around getting body points until they are tired and die. A grave/urn appears at the side of the pool. If in a tub, simply box them in with walls once they're inside.

Death
by Starvation
Starving a Sim is a longer process of death. You will need to remove
any telephones, fridges, and pantries. If they have a phone, they
will keep phoning the pizza guy for food. If they are poor, they
will keep opening up the fridge and a message will pop up telling
you to work for money to buy food. If you do not order more groceries
then your fridge will sit empty and your sim will die. You can also
starve a child for a while, but if under the age of "Teen" it will be taken away before it actually dies.Death details: Starving Sims
bitch and moan about not having food. Eventually they are unable
to do anything but complain for food. They curl up and die on the
floor until Death comes for them. Starving pets will whine for food,
eventually curl up and die.

Death by FireWhen you are planning to kill your Sims by fire, be sure to NOT install a smoke detector or sprinkler. Put rugs by the source of the fire, as it will light up quickly and take out anyone standing near it. Sims with low cooking points using high-end appliances will cause fires more often. Things that cause fires: Fireplaces, Stoves, party fire thrower, lightning Death details:A burning Sim will scream and thrash about in the flames until Death comes for them.

Death by Freezing.
If you have the Seasons add-on, they can now freeze and fall over. They will eventually freeze to death. If you forget to put a roof on your house, the snow will get into the home and freeze them to death in there too.

Stare at the sky and die.
Have your sim go out and "Watch clouds" for a while and a satellite might just drop on its head.

Cow Plant
If you starve your cowplant, it will get hungry and try to tempt a sim with a piece of cake. If they lure in someone, they will eat them up and then your sim can go milk the cow plant.

Reward items.
Aspiration and career awards can give your sims nasty surprises if they use the items while in low aspiration levels. Some can bring your sim close to death while others will kill them completely. The exlixir of life will take days off your sims life if used while your sim has both low aspiration and mood.

Death to Plant Sims.
It seems that plant sims will only go brown and collapse instead of fully dying, which is boring. They can reproduce kids at will, and then you're stuck with a house full of plant sims that just sit in bathtubs, stand near lights and need LOVE. It would be far more interesting if they died and became compost or something, but they don't.

Death to Kid SimsYou can starve a child for a while, but if under the age of "Teen" it will be taken away before it actually dies. You can leave a baby on the ground and it will sleep there etc so you don't have to buy it a crib. You can kill a child with fire but not a toddler or a baby, even if you try to set the crib on fire with them in it. Children will get taken away if they get too cold (with Seasons expansion pack), but do not freeze to death. Toddlers left in cribs outside during the winter are also taken away after several warnings are given.

Child services.
Children left alone too long will be taken from your home. If it's a child, they will wait until after school or even the next morning to attempt to take the child. If it's a toddler or baby, they arrive within the day. It seems that they arrive within 8 hours, so do not leave your child alone at home while your sim goes to work. If the parent is abducted during the night, leaving the child alone, they will get taken away. Children taken away DO get put into adoption, and if other sims in the nieghborhood go to adopt, they just might get that child. Parents who lose a child can not adopt another.

Trapping and making
miserable.Trapping Sims in their homes is
a fun way to watch them slowly die. By having no doors, they can't
go get food, have friends or dispose of the trash properly. Garbage
builds up, cockroaches & flies appear, and the hygiene levels
drop. Bills pile up, the repo man takes things away and pretty
soon your Sim is crying in an empty house.

By making the house really small, not giving them
proper toilets (use the outdoor portipotty), no beds (make them
sleep on the ground or on a crappy couch), you can make your sims
tired and unhappy. Not giving them a proper bed makes it so their
energy is always low. This works for both adult and kid sims.

Buying the cheapest appliances insures
that they will break down quicker. Dishwashers make a huge mess
when they're broken, as well as showers.